/*
 *  linux/kernel/serial.c
 *
 *  (C) 1991  Linus Torvalds
 */

/*
 *	serial.c
 *
 * This module implements the rs232 io functions
 *	void rs_write(struct tty_struct * queue);
 *	void rs_init(void);
 * and all interrupts pertaining to serial IO.
 */

#include <linux/tty.h>
#include <linux/sched.h>
#include <asm/system.h>
#include <asm/io.h>

#define WAKEUP_CHARS (TTY_BUF_SIZE / 4)

extern void rs1_interrupt(void);
extern void rs2_interrupt(void);

static void init(int port) {
    outb_p(0x80, port + 3); /* set DLAB of line control reg */
    outb_p(0x30, port);     /* LS of divisor (48 -> 2400 bps */
    outb_p(0x00, port + 1); /* MS of divisor */
    outb_p(0x03, port + 3); /* reset DLAB */
    outb_p(0x0b, port + 4); /* set DTR,RTS, OUT_2 */
    outb_p(0x0d, port + 1); /* enable all intrs but writes */
    (void)inb(port);        /* read data port to reset things (?) */
}

void rs_init(void) {
    set_intr_gate(0x24, rs1_interrupt);
    set_intr_gate(0x23, rs2_interrupt);
    init(tty_table[1].read_q.data);
    init(tty_table[2].read_q.data);
    outb(inb_p(0x21) & 0xE7, 0x21);
}

/*
 * This routine gets called when tty_write has put something into
 * the write_queue. It must check wheter the queue is empty, and
 * set the interrupt register accordingly
 *
 *	void _rs_write(struct tty_struct * tty);
 */
void rs_write(struct tty_struct *tty) {
    cli();
    if (!EMPTY(tty->write_q))
        outb(inb_p(tty->write_q.data + 1) | 0x02, tty->write_q.data + 1);
    sti();
}
